Many electrical devices include an internal bulk power supply (BPS) used to convert alternating current (AC) power supply signals to lower voltage direct current (DC) power supply signals. Often a connector is attached to the chassis of the electrical device allowing a separate power cord to plug into the device. The connector is electrically connected to the bulk power supply within the chassis, often with wires from the connector to the BPS.
This common configuration creates a number of problems. Many electrical components, such as integrated circuits, may be susceptible to electromagnetic interference (EMI) inherent in high frequency components of the AC power supply signals. A variety of methods are commonly used to reduce this interference. AC line filters are used to reduce the high frequency components of the AC power supply signals. Shielding is often used around the power supply to contain high frequency emissions from the bulk power supply within the system. However, shielding adds to cost and makes replacement of the power supply more difficult.